By PAUL A. WEISSMAN

common reaction to the writings of the conservative legal scholar Richard A. Epstein is that they are simultaneously outrageous and completely convincing. Epstein,
the James Parker Hall Distinguished Service Professor of Law at the University of Chicago, has made a career of presenting cogent cases for radical libertarian positions, including proposals to end most environmental regulation, permit
a free market in human organs and repeal nearly all antidiscrimination and labor laws. However, in ''Principles for a Free Society,'' Epstein refers only glancingly to specific public policy questions and instead
attempts a systematic theoretical defense of laissez-faire economics. The result is a closely reasoned but generally accessible work that offers a coherent, impressively detailed theory of the proper function of law and the state.

Epstein begins with the utilitarian premise that laws are justified only if they increase social welfare. He defines social welfare not as some overarching public interest but as the sum of all the gains and losses that accrue to private individuals.
From this principle, following classical utilitarian philosophers like Jeremy Bentham, Epstein derives the legal rights of individuals to control their own bodies, to hold property and to exchange property (including their own labor)
through binding contracts.

But Epstein is far too sophisticated a thinker to advocate a government that can only defend life and property and enforce contracts -- what opponents of laissez-faire once derided as a ''night watchman state.'' The real gist of his
book is a careful effort to define just what other powers the state should have. To that end, Epstein explores how to draw a line between property whose value is maximized by private ownership -- the usual situation -- and property,
like parks and waterways, that is more valuable when publicly owned. Similarly, Epstein examines at great length the conditions in which government should compel involuntary exchanges of property to achieve a public benefit -- for
example, by levying taxes or condemning land. To give the barest of summaries: he considers such forced exchanges appropriate if and only if no individual is left worse off, at least some individuals benefit and the beneficiaries cannot
obtain the same results by private contract. Epstein sharply distinguishes such beneficial forced exchanges from forced redistributions like Social Security and Medicare payments, which merely pass wealth from some to others and usually,
in his view, entail a net social loss.

Epstein develops these ideas through discussions of a wide range of legal and other topics, from the uses of altruism to the ethics of journalists to the regulation of railroads. Often, he raises fascinating and instructive issues in the economic analysis
of law. Thus he explains, among other matters, why fundamentally different systems of water law apply in the Eastern and Western United States; why ownership of a natural cavern should be assigned to the owner of the land on which
its mouth is located, rather than to owners whose land it passes under; and why a land developer should be permitted to sue a nearby factory for creating a nuisance even if the factory was operating long before the developer's
arrival. The pleasures of reflecting on such puzzles are almost enough to make one wish one were in law school again.

Of course, to be dazzled by Epstein is by no means necessarily to agree with him. For all its air of tough-minded realism, his free market theory is an essentially utopian construct. The wholesale dismantling of government it calls for seems inconceivable
in our era, and even Epstein appears resigned at least to the continued existence of Social Security and Medicare. But underlying his theory's political inconsequence is a more basic departure from political reality. As a consistent
utilitarian, Epstein judges the desirability of social arrangements by their efficiency, not by whether they comport with any inherent human rights. Even slavery, at bottom, is prohibited in his view because it wastes human talent,
rather than because it is wrong by definition. In the past, in fact, Epstein has been so true to his principles as to declare, notoriously, that it is a difficult question whether the law should enforce contracts in which a person
voluntarily sells himself into slavery. This mode of reasoning is profoundly foreign to the overwhelmingly rights-oriented character of American political discourse. Epstein is a spiritual outsider in a culture that teaches its citizens
that they have an inalienable right to be free people, and indeed innate rights to privacy, legal equality and life-saving medical care.

pstein is fond of noting that well before there were law professors versed in economics, human societies tended to establish customs and laws
that maximized their economic resources. We hear in his book of aborigines who efficiently assigned rights to use tribal lands, ancient Roman lawyers who devised productive concepts of property ownership and, most of all, judges in
19th-century England and America who made law based on instinctive economic logic. The one society the book depicts as unable to conform its laws to economic logic is the one Epstein himself lives in, the 20th-century welfare state.
Epstein never addresses the question why our own society is, by his lights, so peculiarly misgoverned. But his answer is plain to see: it is because our laws are not made primarily by judges with an intuitive grasp of economics, but
by the institutions of mass democracy. With its commitment to popular values and belief in rights, democracy subverts his strict utilitarian calculus. The United States maintains statutes banning racial discrimination in employment
because its citizens almost unanimously believe minorities are entitled to such laws, regardless of whether they reduce net social welfare, as Epstein says they do.

The popularity of these and other laws Epstein opposes seems in fact to belie his claims that they reduce net social efficiency -- but that is another argument. ''Principles for a Free Society'' suggests many such arguments, and will
provoke passionate responses from many readers. But even readers disposed to debate with Epstein will find themselves challenged by a powerful and original intellect.

Paul A. Weissman is an adjunct professor at Seton Hall University School of Law.